REFLECTOR: Nose Cooler Pressure Study

Sat Oct 10 21:15:06 CDT 2009

Brent,

What kind of engine cooling inlets do you have?  I have under wing (not
arm pit type) and think they are not very efficient.

Jon

N956DR

1992 Std RG

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brent Bourgeois
Sent: Saturday, October 10, 2009 6:59 PM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Nose Cooler Pressure Study

Scott,

I have spent a lot of time getting my oil cooler working properly.
Before cutting anything, please do a basic pressure study to understand
what is going on. All you need is a plastic tube about 1 inch in front
of the cooler and one in the exit duct. Route them inside and use a
airspeed indicator to get an inlet press and an outlet press. The key is
to maximize the differential.  

I have pages of data that prove (at least on my plane ) that the problem
is positively not getting the air in, but getting it out. 

One example is : 155mph on the pitot, 88mph on the cooler face and 10
mph in the exit duct. I was eventually able to get the exit duct to 0.
This 88mph proved to be the max oil cooler inlet speed all the way past
220 pitot speed. 

I think that once the inlet pressures up, the air stops entering and
flows on by. Once I got max vacuum possible behind the cooler I was able
to block off some of the (weird NACA type)  inlet and not raise the oil
temp.

I believe the trick is to find a reverse scoop or lip arrangement that
maximizes the air extraction

I had thermocouples on the cooler inlet and outlet lines. The front
cooler is worth 15 to 20 degrees in oil temp.

I also found this method very useful at maximizing engine cooling while
making the air inlets smaller. 

Let me know if I can help.

Brent 

N61VB

Std RG

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